Windshields are a standard feature found in many vehicles including cars, trucks, motorcycles, boats, and airplanes. In order to keep a windshield clean, vehicles are usually provided with at least one windshield wiper. The windshield wiper is moved across the surface of the windshield, typically in a back and forth pivotal motion, along the surface of the windshield. In operation, windshield wipers clear precipitation, smudges, stains, and debris from windshields.
A windshield wiper assembly is often comprised of a wiper connected to a wiper arm. The wiper arm is connected to a drive motor and mounted so that it can move with respect to the windshield, typically in a oscillating motion. The wiper arm may include a spring or other resilient element which biases the wiper against the windshield. This allows the wiper to clear the windshield of precipitation and other obstructions, providing a clear view to an operator.
The wiper typically consists of a rubber wiper blade connected to a backing or mounting structure. A variety of different connections may attach the wiper to the wiper arm. For example, the backing of the wiper may be slidably engaged by clamping means at various locations. The clamping means in turn connects to the wiper arm. Other types of quick connector type structures have been developed for wipers and are well known in the art.
Because a clear view is necessary for safe operation of a vehicle, wiper performance is extremely important. Poor wiper performance results in wiper chatter and precipitation streaks. If not designed properly, wipers may also undergo excessive wear requiring frequent replacement. The problem with traditional wiper blades is that they are given a standard radius of curvature while actual windshields vary extensively in their amount of curvature. This results in less than optimal performance of the wiper blade leading to streaking where the radius of curvature of the blade is not enough or to excessive wear when the radius of curvature is too much.
Another problem with traditional wipers is chatter. Chatter is a vibration of the wiper along the windshield. Wiper chattering is undesirable because it leaves streaks on the windshield, results in excess wear on the wiper blade, and creates a sound unpleasant to the operator. Chatter may occur when the friction between the wiper blade and the windshield becomes so great that the wiper blade sticks to the windshield. When this happens, the blade begins to stretch. When the force exerted on the blade by the wiper arm overcomes the friction force between the blade and the windshield, the wiper will be suddenly released, causing it to hop or bounce across the surface of the windshield. Chatter may also result from the wiper sweeping the windshield at an improper angle. The tip of the wiper blade is often connected to the wiper in a manner which allows it to pivot during operating. As the wiper oscillates, the blade will pivot from one direction to the other in accordance with the wiper. In certain circumstances the wiper may fail to pivot properly when the wiper changes directions. When the wiper is swept across the windshield at this improper angle, it will vibrate and cause chatter until the wiper rights itself. Additionally, a high rate of air flowing over the windshield wiper can produce lift, causing the wiper to vibrate and possibly lift from the windshield, resulting in chatter.